Filter mask



FIG. 1 is a perspective view of a filter mask showing my new design, with the filter partially removed;

FIG. 2 is a perspective view of the filter mask shown in a position of use;

FIG. 3 is a front elevational view of the filter mask, with the filter attached;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a left side view of my design;

FIG. 6 is a right side view of my design;

FIG. 7 is a top plan view thereof; and,

FIG. 8 is a bottom plan view thereof.

The dash-dot-dot broken lines showing of the human form in FIG. 2 illustrates environmental subject matter and forms no part of the claimed design. 

CLAIM The ornamental design for a filter mask, as shown and described. 